http://dl.dropbox.com/u/2940017/radioengines.rar these provide somewhat of a military ambience everytime you drive around give it a shot! (you might want to back up your sounds...)
I replaced some of my sounds with some of the BF2 vehicle sounds. Now I lost them due to nub W7 Beta expiring (D, so I'll give this a try *EDIT* Tested a bit now, they are quite....lulz...or something, just that it's a pure annoyance when you're surrounded by 8 other apcs/tanks >.<
Make It as a radar ambiance, have like 15 of these, play them at random times when inside the radar. I've been wanting to do it for a long time.